Chassis: 408336Rarest of all factory fitted coachwork on the 500/540 K is the Autobahn Kurier fastback coupe. As the name suggest this bodystyle was originally developed to travel at high speeds on Germany's newly built highways. Ironically no German ever bought an Autobahn Kurier. The first example was shown at the 1934 Berlin Motor Show, presumably equipped with a 500 K engine. It is believed that only two examples were ever sold; one to the Shah of Persia and the second to a Spanish Professor called Ignacio Barraquer.

Both cars were fitted with the larger 540 engine but it is believed that the Shah's Autobahn Kurier was in fact the Berlin show car. It was shipped to Persia with an empty Supercharger for reliability reasons. Professor Barraquer proved that the fully equipped 540 K was resilient enough to survive harsh desert conditions as he travelled through most of North Africa in 1938. The first car remains in Iran until this very day and has not been seen for many decades. The Spanish car was also unseen for many, many years until it was finally sold by the Barraquer family to the United States in 2004.

Immediately after arriving in North America, it was sent to master restorer Paul Russell. He meticulously prepared the exceptionally rare Mercedes-Benz for the 2006 Pebble Beach Concours d'Elegance. Before the car was shown, it changed hands once more and joined the largest private Mercedes collection in the world. Needless to say, it was very well received at Pebble and won its class. It was one of the four nominees picked for the Best of Show award. In one of the most controversial Pebble results, the Autobahn Kurier lost to a Daimler Double Six Roadster.

After its 'debut' at Pebble, the aerodynamic 540 K went back into hiding until the 2008 Concorso d'Eleganza Villa d'Este. Here some of the injustice was flushed away as it was awarded the Coppa d'Oro, the best of show by public referendum.